Adding issue stats badge for pull requests

Author: kdinev

README.md

@@ -4,6 +4,7 @@
 [![Build Status](https://travis-ci.org/IgniteUI/igniteui-angular.svg?branch=master)](https://travis-ci.org/IgniteUI/igniteui-angular)
 [![Coverage Status](https://coveralls.io/repos/github/IgniteUI/igniteui-angular/badge.svg?branch=master)](https://coveralls.io/github/IgniteUI/igniteui-angular?branch=master)
 [![Codacy Badge](https://api.codacy.com/project/badge/grade/f7b38e525b504be0aabc891079530521)](https://www.codacy.com/app/kdinev/igniteui-angular)
+[![Issue Stats](http://issuestats.com/github/IgniteUI/igniteui-angular/badge/pr?style=flat)](http://issuestats.com/github/IgniteUI/igniteui-angular)
 
 Use the directives found in `igniteui-angular.js` to use [Ignite UI](http://igniteui.com) controls in [AngularJS](http://angularjs.com) pages. [Work with the running samples here](http://igniteui.github.io/igniteui-angular).